All, I have a question... trying to find out what gear ratio would I need to move to when increasing tire size.

I currently have the 4.6 gears in my 04 Fronty and I am running 33x10.5x15 BFG MT's, only it drives like a dog (even going over overpasses, it down shifts)(and on mountain passes it overheats at 45 mph in 2nd gear). Now I bought street tires 245x70x15 on 10" wheels and I regained all my power (and more), and no more over heating on mountain passes, in fact I can go up them now at 65-70 mph in 3rd gear. The truck is now quick off the line too.

So... if I want to keep this power and mountain pass performance, what gear size would I need to move to if I want to run 33-35" tires? Would 5.14's work or would I need to go lower (doesn't appear this is lower)? Never realized how much power I lost till I switched to these smaller street tires. So what I am asking is would running 5.14 gears with 35" wheels be equivalent to running 4.6 gears with 29" wheels?

Any formula for figuring this out?

With nissan axles you cannot go any lower than 5.13.

New gear ratio = (new tire size/old tire size)* old gear ratio

Thanks for the formula, but by the calculations, going from a 29" stock size with 4.62 gears to a 35" tire, we should be installing 5.57 gears. So are all of you that are running 35's suffering when going up the hills? or are the 5.14's good enough?

Hey Terrance, you out there? Or does anyone know what he is running with those 37" tires?

I'm actually running D-44 axles with 5.38 gears and 35" tires. It does ok given that I have a 4-banger.

I think Terence is running something similar to Checo.

T is running 5.13's I recall on his D44's F&R and he out pulls me on the highway with my 5.13/5.14 H233B comb even though I'm only running 35's but I have a auto.

The 5 speed and headers make a difference on T's rig, the auto sucks some of your power especially on grades. I'm going to headers soon.

This CHART has always helped me in the past. Enjoy. Later...

It really nice to know 4.65 is good for 31-33" tires. Ideal for 31-32" tires. Since I never plan to run anything higher than 33" tires on my truck I don’t think I will ever re-gear again.

Gumybob i know exactly what you are going through. My 99 Expedition i use to tow a couple of my cars is horrible going uphill. It overheats and everything. I have 33's on it, and i need to get some 4.10 gears for the front and rear.

sorry to get off topic but what are the stock gears on the 01-04 frontiers?

quote:

Originally posted by ocelot:
sorry to get off topic but what are the stock gears on the 01-04 frontiers?

2wd came with 4.363 or 4.636
4wd came with 4.636 or 4.9
there is usually a plate on the inside of the drivers door that has your ratio on it.